The present invention relates to an image recording apparatus, and more particularly to an apparatus for recording an image on a photosensitive recording medium by exposing the latter to light through a light-transmissive original or a mask member.
Conventionally, various image recording apparatus of the type described above are known, being divided chiefly into two groups. In the apparatus of one group, a photosensitive recording medium is exposed to light directly through a light-transmissive original. In the apparatus of the other group, a photosensitive recording medium is exposed to light through a mask member which is produced according to image information on a light-transmissive original.
FIG. 3 of the accompanying drawings illustrates a typical conventional color image recording apparatus of the type using the mask member. This apparatus comprises a light-transmissive drum 50 for exposure, a pressure developing device 28, and a heat-fixing device 29. A photosensitive recording medium 24 is drawn from a roll contained in a paper cassette 23, extends round the light-transmissive drum 50, is then fed to the pressure developing device 28, and is finally wound round a take-up reel 37. In the meantime, a mask member 22 is inserted in the apparatus from an insertion port 31 disposed at one side of a housing 20a, is then fed as sandwiched between the light-transmissive drum 50 and the photosensitive recording medium 24, and is finally separated from the photosensitive recording medium 24 and discharged onto a discharge tray 32.
With the mask member 22 thus sandwiched between the light-transmissive drum 50 and the photosensitive recording medium 24, a lamp (light source) 51 built in the light-transmissive drum 50 is lighted to expose the photosensitive recording medium 24 through achromatic resolution filter 52. In the conventional apparatus, the photosensitive recording medium 24 is a color photosensitive sheet coated with photosensitive microcapsules, such as disclosed in U.S. Pat. No. 4,399,209. Accordingly, more than one mask member 22 (to obtain a full-color image, three mask members for red, green and blue) is used. Such plurality of mask members 22 are fed one after another to the light-transmissive drum 50 from the insertion port 31, during which time the photosensitive recording medium 24 is repeatedly moved back and forth in the directions of arrows A, B as the light-transmissive drum 50 rotates in opposite directions. Then the photosensitive recording medium 24 is fed to the pressure developing device 28 where a developer sheet 26 is paid out from a stack contained in a sheet cassette 27 and is laid over the photosensitive recording paper 24. The developer sheet 26 is coated with a developer material, while the photosensitive recording medium 24 is coated on one surface with a layer comprising microcapsules encapsulating dye precursors as a main component. When the microcapsules on the photosensitive recording medium 24 are ruptured as the latter together with the developer sheet 26 is pressed by the pressure developing device 28, the developer material on the developer sheet 26 reacts to the dye precursors on the photosensitive recording medium 24 to develop a visible color image on the surface of the developer sheet 26. Subsequently, in the heat-fixing device, the developer paper 2G is expedited to take on color and is treated to become glassy, whereupon the developer paper 26 is discharged onto another discharge tray 30.
With this arrangement, since the mask member 22 (or the light-transmissive original) and the photosensitive recording medium 24 are brought in tight contact with each other with precision, a picture image with clear contour can be obtained.
However, with this conventional apparatus, it is difficult to perfectly synchronize the feeding of the photosensitive recording paper 24 with the rate of rotation of the light-transmissive drum 50. As a consequence, a deviation would occur between the mask member 22 to be in contact with the peripheral surface of the light-transmissive drum 50 and the photosensitive recording medium 24 outside the mask member 22, thus creating scratches on the surface of the photosensitive recording medium 24 and hence impairing the quality of the picture image.